Electrical measuring instrument.



No. 872,300. PATENTED NOV. 26, 1907. P. MAOGAHAN.

ELEOTRIGAL MEASURING INSTRUMENT.

APPLICATION FILED 0OT.18. 1905.

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ATTORNEY PATENTED NOV. 26, 1907.

P. MAGGAHAN.

ELECTRICAL MEASURING INSTRUMENT.

APPLICATION FILED 00118. 1905.

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UNITED STATES PATENT oinnon.

PAUL MAQGAIIAN, O1! PITTSBURG, PENNSYLVANIA, ASSlGNOIt TO N vIESTI'NLlllO USE ELECTRIC d1. MAN U FAOTURING COMPANY, A CORPORATION 01* PENNSYLVANIA.

ELECTRICAL MEASURING INSTRUMENT.

Specification of Letters Patent.

r mmed Nov. 26,1907.

Application filed Oc r 18. 1905. Serial No. 283339.

To all whom it mwy. concern:

Be it known that 1, PAUL MAoG-AIIAN, a citizen of the United States, and a resident of Pittsbur", in the county of Allegheny vand State of ennsylvania, have invented a new and useful Improvement in Electrical Measuring Instruments, of which the following is a specification.

My invention relates to electrical measuring instruments and it has for its object to provide an instrument by means of which either the voltage of a circuit or the amount of eiiergy traversing the circuit may be measurec In the commercial .testing of electrical incandcscent and are lamps the quantities most usually measured are the drop in potentialinthe, lamps and the energy consumed by them. In order that the testing apparatus may be as compact as possible, it is desirable that a single instrument be provided that shall be capable of measurin both of these quantities independently, an it is further desirable that the instrument be so constructed as to be portable. The purpose of this invention is to provide such an instrument.

Figure 1 of the accompanying drawings is a view, partially in plan and partially in section, of an instrument embodying my invention. ,Fig. 2 is a transverse, sectional view on the line II-I]' of Fig. 1 and Fi 3 is 9. diagrammatic view 01' the circuit relations and connections of the various parts of the instrument.

Rigidly fastened upon the inner or rear face of an insulating plate 1 by means of screws 2, are insulating blocks 3 to which coils 4, "5, 6 and 7 are secured by means of tape or otherwise, thecoils being arran ed in pairs with the faces of the members oi each pair opposing one another. Two other coils 8 and- 9 are mounted, by means of suitable brackets 10, upon a shaft 11 that is provided with bearings 12 and 13 at its upper and lower ends respectively, the coils being thus pivotally supported respectively between the members of the pairs of stationary coils. The inner end of a spiral s ring 14 is secured. to the upper extremity o the shaft 11 and the outer end is connected by means of a bracket 15 with a manually rotatable member 16,

that may be operated by means of a knurled head 17. A pointer 18 that is carried by the rotatable member 10 is adapted to be moved over annular scales 19 and 20, the former of which is graduated in volts as units and the latter in watts as units. An opening 21 is provided in the insulating plate 1 through which projects the free end of a pointer 22 that is attached to the movable coil 9, the

pointer cooperatin with an index 23 on the upper side of the p ate 1 to indicate balancing of the torque of the instrument with the torsion of the spiral spring 14.

The coils 4, 5, 6 and 7 comprise two intercoiled windings 24 and 25, which are res ectively of low and hi h resistance, the win ing 24 being (onnected between a binding ost 26 and a contact terminal 27 of a switc 28 that further comprises contact terminals 29, 30 and'31 and conducting segments 32 and 33 that are mounted upon a switch lever 34 and that are adapted to engage contact terminals 27 and 30 or 29 and 31 respectively.

The winding 25 is connected in series circuit with a resistance .35 between contact terminal 31 and one terminal 360i a socket or receptacle 37 for an incandescent lamp or other suitable translating device, the terminal 36 being also connected to conducting strip 32, and the other terminal of the socket 37 being connected to a binding ost 38.

The switch lever 34 is adapter tobe operated by means of a knurled head 39 that is located upon the upper side of the insulating plate 1 and that is provided with a pointer 40 which cooperates with indices V and W upon the plate to indicate whether the instrument is adjusted. to measure volts or watts.

The movable coils-8 and 9 which are composed of a comparatively high resistance conductor are connected in series relation with a high resistance 41 between the binding post 38 and the conducting piece 33 on the switch lever 34-. A resistance 42 that is approximately equal to the resistance of the winding 24. is connected between the contact terminals 29 and 30 and one terminal of the resistance is connected to the binding post 26.

In the operation of the instrument a lamp or other suitable translating device is placed in the socket 87 and the instrument is con uccted to an external circuit (not shown) by means of the binding posts 26 and 38. If it is desired-to measure the drop of potential in the lamp, the knurled head 39 should be retated until the pointer 40 registers with the index V, the conducting strips 32 and 33 be ing thereby caused to engage contact terminals 29 and 31 respectively. The translating device is then connected in series with the resistance 42 between the bindin r posts, and a circuit is also established in s nut to the translating device through the movable coils 8 and 9, the resistance 41, conducting piece 33, contact terminal 313, the stationary winding 25 and resistance 35. The pointer 22 will then be deflected to the left, and in order to return it to a position opposite the index 23 it becomes necessary to turn the knurled head 17 and the attached pointer 18 in a clockwise direction, the deflection from the zero position of the point-er 1 S necessary to effect this adjustment being indicated upon the scale 19 in volts.

If it is desired to measure the energy absorbed in the translating device, the knurled head 39 should be caused to occupy the position shown in Fig. 1,when conducting pieces 32 and 33 will engage contact terminals 27 and 30, respectively, and the translating device will be connected in series circuit with the stationary Winding 24 between the binding posts by the engagement of the conducting strip 32 with contact terminal 27, a circuit being established also through the movable coils 8 and 9, resistance 41, conducting segment 33 and contact terminal 30 to the binding 0st 26.

It wil be observed that the stationary winding is connected in series with the transiating device while the movable coils are connected in shunt thereto, so that the uantities measured by the instrument wil be the watts f energy expended in the trans lating device, which will be indicated upon the scale 20.

It should be noted that the resistance of the circuit that includes thetranslating device is approximately the same whether the instrument is operated as a wattmeter or as a voltmeter because, in the one case, the

"winding 24 is in the circuit and in the other case, the equivalent resistance 25 is introduced. The amount of resistance in the circuit in shunt to the translating device is less when the instrument operates as a wattmeter than when it operates as a volt-meter because in the former instance only the resistance 41 is induced in the circuit and in the latter instance both resistances 35 and 41 are included, these differences being for the purpose of providing scales of convenient proportions.

The details of construction and arrangement of the parts of the instrument may be considerably varied from what have here been shown and described specifically without whereby the said receptacle may be connected between the circuit terminals in series circuit with the low resistance stationary winding and the movable winding maybe connected in shunt thereto, or whereby the said receptacle may be connected between the circuit terminalsin series with the resistance, and the high resistance stationary winding and the movable winding may be connected in series with each other and in shunt to the receptacle.

. 2. In an electrical measuring instrument, the combination with a receptacle for a translating device, stationary windings respectively of high and low resistance, and a movable winding, of a resistance approximately equal to that of the low resistance stationary winding, and means whereby the said receptacle maybe connected between the circuit terminals in series circuit with the low resistance stationary winding and the movable winding may be connected in shunt thereto, or whereby the said receptacle may be connected between the circuit terminals in series with the resistance, and the high resistance stationary winding and the movable winding may be connected in series with each other and in shunt to the receptacle.

3. In an electrical measuring instrument, the combination with a receptacle for a translating device, stationary windings respectively of high and low resistance, and a movable winding, of' a resistance, and means whereby the circuit relations of the parts may be so adjusted as to cause the instrument to operate either as a voltmeter or as a wattmeter and whereby the said receptacle may be connected in series circuit with the resistance in the former instance and in series circuit with the low resistance stationary winding in the second instance.

4. In an electrical measuring instrument, the combination with a receptacle for a translating device, stationary windings respectively of high and low resistance, and a movable winding, of a resistance approximately equal to that of the low resistance stationary winding, and means whereby the circuit relations of the parts may be so adjusted as to cause the instrument to operate either as a voltmeter or as a wattmeter and whereby the said receptacle may be connected in series circuit with the resistance inthe former instance and in series circuit with .the low 125 resistance stationary winding in the second instance.

5. In an electrical measuring instrument,

10 ance in series circuit with the the coinhination with a receptacle for a translating device, stationary windings respectively of high and low resistance, and a movable winding, of a resistance approximately equal tothat of the low resistance stationary winding, and means whereby the circuit relations of the parts may be so adjusted as to cause the instrument to operate either as a voltmeter or as a wattmeter and the resistsaid receptacle to hemaintained approximately the same under either condition.

In testimony whereof, I have hereunto, subscribed my name this 13th day of October, 1905. 1

S. M. TRUXAL, BIRNEY llmns. 

